Over the holiday of passover, I find myself doing a lot more dishes than normal. We use completely separate dishes for the holiday, since the requirement to eliminate all chametz (leavened products) extends to all of our regular dishes, which have been contaminated from contact with bread products over the course of the year. It’s kind of like cooties.
The chametz prohibition extends to our dishwasher as well, so that means that all dishes during the eight day holiday have to be done by hand. It really makes you appreciate the modern convenience of the dishwasher during the rest of the year.
Dishes, glasses and pots aren’t so bad, but what really drive me nuts is the tupperware. I don’t know why, but there is something about plastic that makes it a magnet for oil and grease. You scrub it with a sponge, soap, and hot water, and you find that it still has a slippery film coating it.
Someone once taught me a trick for how to clean oily tupperwares, and since we are still halfway through the holiday, I thought I would pass it along to my fellow Jews slaving away washing their pesach dishes.
The secret is to eliminate the water and sponge and just use the raw grease cutting power of the soap directly. Here are the steps:
- Remove any food reside from the tupperware (you can use water for this, just make sure to shake the water out so that it doesn’t pool at the bottom).
- Put a squirt of soap directly into the container.
- Use your fingers to spread the soap all along the inside surface of the tupperware. It’s kind of like finger painting. (Add more soap if necessary)
- Once the whole inside of the tupperware is thinly coated in soap, rinse it out with hot water
- Dry the tupperware with a hand towel
When you are done, you will find the container squeaky clean with no oily residue. I’ve done with with all kinds of food, including greasy meat or chicken that leave hard to remove fat. It works like a charm.
So yes, the answer is just soap. Not a trick really, more a technique for exactly how to use it.
Passover is more than half over. Hang in there!
Jeremy Rothman-Shore Blog 
The problem is one of chemistry really. Detergent or soap molecules work by having one positively charged end and one negatively charged end. This allows oily, fatty, greasy, etc dirt particles to attach to one side of the molecule, while allowing water to attach to the other, and then the whole jumbled molecular mess can be flushed away down the drain. (remember fifth grade when you learned that oil and water normally do not mix? this is why we use soap, to act as a bridge between the two)
With traditional cookware like glass, metal, etc, this poses no problem. But with most plastics, there enters a new concern. You may have noticed that a plastic container can build up a static electric charge, making your hair stand on end when you touch it. (again, think to fifth grade science, and scrubbing your shoes across a synthetic nylon carpet and then touching a doorknob) This static charge is a property of the types of polymers used in storage containers, and really most plastics in general, and is able to override the normal operation of the soap molecule, and instead of binding to water, the soap and oil combination instead attaches itself to the plastic container resulting in that oily residue. (and it becomes even more gross when you realize that that residue is actually a mixture of soap and nasty food remnants, a literal disease infested slime)
Using clean soap first, and then a hot water rinse is basically one way of stating the problem; when doing dishes, the soap sits around and attaches to lots of fats and oils in the sink from whatever you’ve washed first (usually the silverware or fragiles like drinking glasses) and then, when you throw the plastic items into the sink, it quickly attracts those molecules to it, where they stick down from the electrostatic charge of the plastics. So really, if you wash the plastic food keepers first, and don’t let them sit in the water and attract the slime, you’ll get much the same result as washing them separately with the soap-first trick.
Sadly, there’s not a lot that can be done to prevent this as it’s an electrostatic property of the plastics used rather than anything to do with the properties of the soap/detergent or how much you use, though using too much dish soap does accelerate it; though I do find that the problem of static electric bonding is more pronounced in the modern clear plastic products than the old-style opaque tupperware (think that seventies orange and green set sitting in grandma’s cupboard) you’ll also find that the plastic handles on cookware is less likely to suffer this problem, between being a different type of plastic, and because it is attached to metal which can draw off the static charge, it is less likely to cause the reaction.
Wow, thank you for the very thorough explanation.
Works great! Thank you!
Just found this tip as had this problem after storing olives in a plastic container. Brilliant! Thanks for posting.
Oh my gosh! Thank you so much for posting this. I have to hand wash dishes for a while and have had such a problem with greasy plastic containers and this made them squeaky clean!!!
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